High-Nickel Cathode Coating and Doping for Cycle Stability
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Solution Overview
Problem
High-nickel positive electrode active materials suffer from reduced structural stability and cycling performance due to increasing nickel content, affecting the capacity and storage performance of lithium-ion secondary batteries.
Innovation Solution
A modified high-nickel ternary positive electrode material is developed with an inner core doped with M1, M2, and W, a surface layer doped with Co, and outer coating layers containing Al and B compounds, enhancing structural stability and reducing high-valent nickel ions to improve cycling and storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content in the positive electrode active material is increased to achieve high energy density, then capacity is improved, but structural stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-nickel ternary material (Li1+a[NixCoyMnz]O2 with x≥0.80) and the outer shell contains low-nickel ternary material (Li1+b[Ni1-yCoyMnz]O2 with y≤0.60). This allows the high-capacity inner core to be protected by the structurally stable outer shell, resolving the contradiction between high nickel content for capacity and structural stability.
Solution Approach 2:
The patent uses composite materials by combining high-nickel ternary material with low-nickel ternary material in a core-shell architecture. The composite structure leverages the high capacity of high-nickel material while the low-nickel material provides structural stability, effectively resolving the contradiction between capacity and structural stability.
2Quantity of substance
If nickel content is increased to improve capacity, then energy density is improved, but cycling performance deteriorates
Solution Approach 1:
The core-shell structure with high-nickel inner core and low-nickel outer shell allows the high-capacity material to be isolated from direct contact with electrolyte, reducing degradation during cycling. The outer shell acts as a protective layer that maintains structural integrity over multiple charge-discharge cycles, improving cycling performance while preserving high capacity.
Solution Approach 2:
The low-nickel outer shell serves as a protective cushion that prevents direct exposure of the high-nickel inner core to the electrolyte and mechanical stress during cycling. This beforehand protection reduces structural degradation and maintains cycling performance over extended battery life.
3Quantity of substance
If nickel content is increased to achieve high energy density, then capacity is improved, but storage performance deteriorates
Solution Approach 1:
The core-shell structure with high-nickel inner core and low-nickel outer shell protects the high-capacity material from environmental degradation during storage. The outer shell acts as a barrier that reduces side reactions with electrolyte and prevents structural collapse during prolonged storage, maintaining storage performance while enabling high capacity.
4Quantity of substance
If high-nickel ternary material is used to improve capacity, then energy density is improved, but thermal stability deteriorates
Solution Approach 1:
The core-shell structure with high-nickel inner core and low-nickel outer shell improves thermal stability by having the low-nickel material on the surface that is less prone to thermal runaway. The outer shell acts as a thermal barrier that delays and mitigates thermal degradation, allowing the high-capacity inner core to be utilized safely.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified electrode material significantly improves cycling and storage performance by increasing structural stability, reducing side reactions, and maintaining high capacity through synergistic doping and coating, resulting in enhanced capacity and rate performance.
Implementation Method 1
the inner core includes a high-nickel ternary positive electrode material matrix, the matrix being doped with M1, M2, and W
Implementation Method 2
the high-nickel ternary positive electrode material matrix is doped with three kinds of ions (namely M1, M2, and W) synergistically, so that structural stability of the high-nickel ternary positive electrode material can be more effectively increased
Implementation Method 3
the surface layer of the high-nickel ternary positive electrode material is also doped with Co, so that an amount of high-valent nickel ions contained in the surface layer of the high-nickel ternary positive electrode material can be effectively reduced
Implementation Method 4
an amount of high-valent nickel ions contained in the surface layer of the high-nickel ternary positive electrode material can be effectively reduced
Implementation Method 5
the high-nickel ternary positive electrode material is uniformly coated with an inner layer containing a Co compound and an outer layer containing an Al compound and a B-containing compound
Implementation Method 6
so that an amount of lithium impurities contained on the surface can be effectively reduced
Implementation Method 7
the high-nickel ternary positive electrode material is uniformly coated with an inner layer containing a Co compound and an outer layer containing an Al compound and a B-containing compound
Implementation Method 8
interface side reactions between the high-nickel ternary positive electrode material and the electrolyte can be further effectively inhibited
Data Source
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AI summary
Provided in the present application is a modified high-nickel ternary positive electrode material, containing a core, an inner coating layer and an outer coating layer. The core contains a high-nickel ternary positive electrode material matrix, which is doped with M1, M2 and W, wherein M1 is one of Mo, Zr, Ti, Sb, Nb and Te; and M2 is one of Mg, Al, Ca, Zn and Sr. The chemical formula of the high-nickel ternary positive electrode material matrix doped with M1, M2 and W is Li1+a[NixCoyMnzMlbM2cWd]O2, wherein 0.65 ≤ x < 1; 0 < y < 0.3; 0 ≤ z < 0.3; 0 < a < 0.2; 0< b < 0.1; 0 < c < 0.1; 0 < d < 0.1; x + y + z + b + c + d = 1; and optionally, 0.8 ≤ x < 1. The surface layer of the core is further doped with Co. The inner coating layer is a Co-containing compound, and the outer coating layer is an Al-containing compound and a B-containing compound. The present application also relates to a method for preparing a modified high-nickel ternary positive electrode material, and a secondary battery, a battery module, a battery pack and a power-consuming apparatus.